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A three dimension forming apparatus includes a model material ejection
unit that ejects a model material, a support material ejection unit that
ejects a support material, and a controller that controls the model
material ejection unit and the support material ejection unit such that
the model material and the support material are arranged as a support
structure in an arrangement pattern containing the model material and the
support material, the support structure supporting or protecting a
three-dimensional structure to be formed by the model material.

1. A three dimension forming apparatus, comprising: a model material
ejection unit that ejects a model material; a support material ejection
unit that ejects a support material; and a controller that controls the
model material ejection unit and the support material ejection unit such
that the model material and the support material are arranged as a
support structure in an arrangement pattern containing the model material
and the support material, the support structure supporting or protecting
a three-dimensional structure to be formed by the model material.

2. The three dimension forming apparatus according to claim 1, wherein
the arrangement pattern is a grid-like pattern in which the model
material and the support material are alternately arranged.

3. The three dimension forming apparatus according to claim 1, wherein
the arrangement pattern is a gradation-like pattern in which, as the
support structure is positioned closer to the three-dimensional
structure, the proportion of the support material in the support
structure increases, and, as the support structure is more distant from
the three-dimensional structure, the proportion of the model material in
the support structure increases.

4. The three dimension forming apparatus according to claim 1, wherein
the arrangement pattern is a random pattern in which the model material
and the support material are randomly arranged.

5. The three dimension forming apparatus according to claim 1, wherein
the controller controls the model material ejection unit and the support
material ejection unit such that each of the model material and the
support material is not continuously arranged in a height direction of
the three-dimensional structure.

6. The three dimension forming apparatus according to claim 1, wherein
the controller determines a height required for the support structure
from modeling data of the three-dimensional structure for each of a
plurality of segmented regions obtained by segmenting a projection region
obtained by projecting the three-dimensional structure in a height
direction, and controls the model material ejection unit and the support
material ejection unit such that the model material and the support
material are arranged as the support structure having the height in the
arrangement pattern.

7. The three dimension forming apparatus according to claim 1, wherein
the support material is water-soluble or thermal-fusible.

8. A three dimension forming method, comprising: controlling ejection of
a model material and a support material such that the model material and
the support material are arranged as a support structure in an
arrangement pattern containing the model material and the support
material, the support structure supporting or protecting a
three-dimensional structure to be formed by the model material.

9. A non-transitory computer readable medium storing a three dimension
forming program, which allows a computer to function as the controller of
the three dimension forming apparatus according to claim 1.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims priority under USC 119 from
Japanese Patent Application No. 2016-056160, filed on Mar. 18, 2016.

BACKGROUND

[0002] (i) Technical Field

[0003] The present invention relates to a three dimension forming
apparatus, a three dimension forming method and a non-transitory computer
readable medium storing a three dimension forming program.

[0004] (ii) Related Art

[0005] Various technologies for forming a three-dimensional structure are
known. For example, in a technology called rapid prototyping, based on
the data of a standard triangulated language (STL) format in which the
surface of a three-dimensional structure is described as a set of
triangular polygons, a sectional shape sliced in the laminating direction
of the three-dimensional structure is calculated, and each layer is
formed according to the sectional shape, thereby forming the
three-dimensional structure.

[0007] In the inkjet method, a treatment for forming a model material
layer by selectively ejecting a model material, such as a photocurable
resin, from an inkjet head to a modeling platform and by curing the model
material is repeated to laminate plural model material layers, thereby
forming a three-dimensional structure. Further, in the inkjet method, a
support material for supporting the model material during the formation
of a three-dimensional structure is supplied to the modeling platform. In
a case where there is an overhang portion, that is, a flared portion, in
a three-dimensional structure, the support material mainly serves to
support the overhang portion until the formation of the three-dimensional
structure is completed, and is removed after the formation of the
three-dimensional structure is completed. Further, the support material
is used not only to support the overhang portion but also, in a case
where the three-dimensional structure has a shape having a nearly
vertical surface, such as a cube, for example, to protect the surface by
preventing the dripping on the surface. Moreover, the support material is
also used to cover and protect the model material in order to prevent the
formation-completed portion from being degraded by excessive irradiation
with UV light, in a case where a method of UV-curing of the model
material is used in the formation of the three-dimensional structure.

SUMMARY

[0008] According to an aspect of the invention, there is provided a three
dimension forming apparatus, including: a model material ejection unit
that ejects a model material; a support material ejection unit that
ejects a support material; and a controller that controls the model
material ejection unit and the support material ejection unit such that
the model material and the support material are arranged as a support
structure in an arrangement pattern containing the model material and the
support material, the support structure supporting or protecting a
three-dimensional structure to be formed by the model material.

BRIEF DESCRIPTION OF DRAWINGS

[0009] Exemplary embodiments of the present invention will be described in
detail based on the following figures, wherein:

[0010] FIG. 1 is a block diagram of a three dimension forming apparatus;

[0011] FIG. 2 is a side view of the three dimension forming apparatus;

[0012] FIG. 3 is a flowchart of processing to be executed by a controller
according to a first exemplary embodiment;

[0013] FIG. 4 is a side view of a three-dimensional structure;

[0014] FIG. 5 is a view for illustrating a section of the
three-dimensional structure;

[0015] FIG. 6 is a view showing an example of a sectional image;

[0016] FIG. 7 is a view for illustrating a section of the
three-dimensional structure;

[0017] FIG. 8 is a view showing an example of a sectional image;

[0018] FIG. 9 is a view for illustrating a section of the
three-dimensional structure;

[0019] FIG. 10 is a view showing an example of a sectional image;

[0020] FIG. 11 is a view for illustrating a region needing a support
structure;

[0021] FIG. 12 is a view for illustrating a region needing a support
structure;

[0022] FIGS. 13A to 13C are views showing an example of an arrangement
pattern of a model material and a support material;

[0023] FIG. 14 is a view showing an example of an arrangement pattern of a
model material and a support material in a height direction;

[0024] FIG. 15 is a view showing an example of an arrangement pattern of a
model material and a support material in a height direction;

[0025] FIG. 16 is a flowchart of processing to be executed by a controller
according to a second exemplary embodiment;

[0026] FIG. 17 is a view for illustrating the prediction of a support
structure;

[0027] FIGS. 18A and 18B are views for illustrating a projection region of
a three-dimensional structure;

[0028] FIG. 19 is a view showing an example of the division of the
projection region;

[0029] FIG. 20 is a view showing an example of a support structure with
respect to each block;

[0030] FIG. 21 is a view showing an example of a support structure with
respect to each block;

[0031] FIG. 22 is a view showing a resolution pattern for scanning by a
three dimension forming apparatus in Examples, the resolution pattern
having a modeling pattern in which square projections are arranged in a
grid pattern; and

[0032] FIG. 23 is a view showing the results of experiments on the
viscosity adjustment of a support material.

DETAILED DESCRIPTION

First Exemplary Embodiment

[0033] Hereinafter, the present exemplary embodiment will be described in
detail with reference to the drawings.

[0034] FIG. 1 is a block diagram of a three dimension forming apparatus 10
according to the present exemplary embodiment. As shown in FIG. 1, the
three dimension forming apparatus 10 is configured to include a
controller 12.

[0036] The I/O 12E is connected with function units, such as a model
material accommodation unit 14, a model material ejection head 16, a
support material accommodation unit 18, a support material ejection head
20, a UV light source 22, an XY scanning unit 24, a modeling platform
lifting unit 26, a cleaning unit 28, a storage unit 30, and a
communication unit 32.

[0037] The model material accommodation unit 14 accommodates a model
material for forming a three-dimensional structure. The model material is
composed of a UV-curable resin having a property of being cured by the
irradiation with ultraviolet (UV) light, that is, ultraviolet rays.

[0038] A detailed description of the model material will be described
later.

[0039] The model material ejection head 16 ejects the model material
supplied from the model material accommodation unit 14 by an inkjet
method in accordance with an instruction from the CPU 12A.

[0040] The support material accommodation unit 18 accommodates a support
material for supporting or protecting a three-dimensional structure. The
support material is used to support the overhang portion (flared portion)
of a three-dimensional structure until the formation of the
three-dimensional structure is completed, and is removed after the
formation of the three-dimensional structure is completed. Further, for
example, in the case where the three-dimensional structure, similarly to
a cube, has a shape having a nearly vertical surface, the support
material is used to protect the surface by preventing the dripping of the
surface. Moreover, the support material is also used to cover and protect
the model material in order to prevent a three-dimensional structure from
being degraded by the irradiation with UV light. The support material,
similarly to the model material, is composed of a UV-curable resin having
a property of being cured by the irradiation with UV light.

[0041] A detailed description of the support material will be described
later.

[0042] The support material ejection head 20 ejects the support material
supplied from the support material accommodation unit 18 by an inkjet
method in accordance with an instruction from the CPU 12A.

[0043] A piezo-type (piezoelectric type) ejection head in which droplets
of each material are ejected by pressure is applied to each of the model
material ejection head 16 and the support material ejection head 20. Each
of the ejection heads is not limited thereto as long as it is an inkjet
type ejection head, and may be an ejection head in which each material is
ejected by pressure generated by a pump.

[0044] When the support material is ejected from the support material
ejection head 20, the support material is heated to 40.degree. C. to
90.degree. C. (preferably, 45.degree. C. to 80.degree. C., and more
preferably 50.degree. C. to 75.degree. C.).

[0045] Even when the model material is ejected from the model material
ejection head 16, it is preferable that the heating temperature of the
model material is within the same range as above.

[0046] The UV light source 22 irradiates the model material ejected from
the model material ejection head 16 and the support material ejected from
the support material ejection head 20 with UV light to cure the model
material and the support material. The UV light source 22 is selected
depending on the kinds of the model material and the support material. As
the UV light source 22, for example, a device having a light source, such
as a metal halide lamp, a high-pressure mercury lamp, an
ultrahigh-pressure mercury lamp, a deep ultraviolet lamp, a lamp exciting
a mercury lamp without electrode from the outside using microwaves, an
ultraviolet laser, a xenon lamp, or UV-LED, is applied.

[0047] An electron beam irradiation device may be used instead of the UV
light source 22. As the electron beam irradiation device, for example, a
scanning type, curtain type or plasma discharge type electron beam
irradiation device is exemplified.

[0048] As shown in FIG. 2, the model material ejection head 16, the
support material ejection head 20, and the UV light source 22 are mounted
on a scanning axis 24A provided with the XY scanning unit 24. The model
material ejection head 16 and the UV light source 22 are mounted on the
scanning axis 24A to be spaced apart from each other by a predetermined
distance W. The support material ejection head 20 is mounted on the
scanning axis 24A to be adjacent to the model material ejection head 16.
The position of the model material ejection head 16 and the position of
the support material ejection head 20 may be reversed. That is, in FIG.
2, the model material ejection head 16 faces the side of the UV light
source 22, but the support material ejection head 20 may face the side of
the UV light source 22.

[0049] The XY scanning unit 24 drives the scanning axis 24A such that the
model material ejection head 16, the support material ejection head 20,
and the UV light source 22 move in X and Y directions, that is, are
scanned on a XY plane.

[0050] The modeling platform lifting unit 26 lifts a modeling platform 34
shown in FIG. 2 in a Z-axis direction. The CPU 12A, at the time of
forming a three-dimensional structure, controls the model material
ejection head 16, the support material ejection head 20, and the UV light
source 22 such that the model material and the support material are
ejected onto the modeling platform 34, and the ejected model material and
support material are irradiated with UV light. Further, the CPU 12A
controls the XY scanning unit 24 such that the model material ejection
head 16, the support material ejection head 20, and the UV light source
22 are scanned on the XY plane, and controls the modeling platform
lifting unit 26 such that the modeling platform 34 gradually descends in
the Z-axis direction.

[0051] The CPU 12A, at the time of forming a three-dimensional structure,
controls the modeling platform lifting unit 26 such that the distance
from the model material ejection head 16, the support material ejection
head 20, and the UV light source 22 to a three-dimensional structure 40
on the modeling platform 34 in the Z-axis direction is a predetermined
distance h0 or more in order for the model material ejection head 16, the
support material ejection head 20, and the UV light source 22 not to be
in contact with three-dimensional structure 40 on the modeling platform
34.

[0052] The cleaning unit 28 has a function of performing a cleaning by
sucking the materials adhered to the nozzles of the model material
ejection head 16 and the support material ejection head 20. For example,
the cleaning unit 28 is provided in a save area outside the scanning
range of the model material ejection head 16 and the support material
ejection head 20, and performs a cleaning by saving the model material
ejection head 16 and the support material ejection head 20 in the save
area at the time of performing the cleaning.

[0053] The storage unit 30 stores a three dimension forming program 30A,
modeling data 30B, and support material data 30C, which will be described
later.

[0054] The CPU 12A reads the three dimension forming program 30A stored in
the storage unit 30. Further, the CPU 12A records the three dimension
forming program 30A in a recording medium, such as CD-ROM, and may
execute the recorded three dimension forming program 30A by reading this
program by a CD-ROM drive.

[0055] The communication unit 32 is an interface for performing data
communication with an external device outputting the modeling data 30B of
a three-dimensional structure.

[0056] The CPU 12A controls the respective function units in accordance
with the modeling data 30B transmitted from the external device, thereby
forming a three-dimensional structure.

[0057] Next, operations of the present exemplary embodiment will be
described. FIG. 3 shows a flowchart of the three dimension forming
program 30A to be executed by the CPU 12A. The processing in FIG. 3 is
executed when the formation of a three-dimensional structure is
instructed from the external device.

[0058] Further, hereinafter, a case of forming a three-dimensional
structure 40 as shown in FIG. 4 will be described as an example. As shown
in FIG. 4, the three-dimensional structure 40 has a rabbit shape.

[0059] In step 100 (S100), modeling data 30B of the three-dimensional
structure 40 are received from an external device, and the received
modeling data 30B are stored in the storage unit 30. As the format of the
modeling data 30B of the three-dimensional structure 40, for example, a
standard triangulated language (STL) format, which is a format of data
expressing a three-dimensional shape, is used. Therefore, the
three-dimensional structure 40 shown in FIG. 4 is expressed as a set of
triangular polygons. The format of data expressing a three-dimensional
shape is not limited to STL, and other formats may be used.

[0060] In step 102 (S102), lamination data (slice data) of the
three-dimensional structure 40 are created in accordance with the
modeling data 30B received in step 100 (S100). Specifically, a slice
plane, which is parallel to a ground plane (XY plane) in which the
three-dimensional structure 40 is grounded to the modeling platform 34,
is shifted in a height direction (Z-axis direction) for each
predetermined lamination pitch, and the intersection point of the slice
plane and the polygons is determined, thereby creating slice data
expressing the sectional image of the three-dimensional structure 40 in
the slice plane. Such slice data are created for each sectional image
sliced to the height of the three-dimensional structure 40 for each
predetermined lamination pitch.

[0061] For example, as shown in FIG. 5, the sectional image in the slice
plane 52 parallel to the ground plane 50 becomes a sectional image 54 as
shown in FIG. 6. Further, for example, as shown in FIG. 7, the sectional
image in the slice plane 56 parallel to the ground plane 50 becomes a
sectional image 58 as shown in FIG. 8. Moreover, for example, as shown in
FIG. 9, the sectional image in the slice plane 60 parallel to the ground
plane 50 becomes a sectional image 62 as shown in FIG. 10.

[0062] In step 104 (S104), a support structure necessary for supporting
the three-dimensional structure 40 is determined based on the slice data
of each layer of the three-dimensional structure 40 created in the step
102 (S102).

[0063] Although the three-dimensional structure 40 is formed by
sequentially laminating the model material on the modeling platform 34,
in the case where, for example, as the lower portion of a rabbit ear
shown in FIG. 4, a portion in which the lower side of the
three-dimensional structure 40 becomes a space, so called, an overhang
portion exists, there is a need to support the overhang portion from
under. Therefore, a support structure 42, which is a space under the
overhang portion, is determined based on the slice data of each layer.

[0064] Specifically, for example, slice data of two adjacent layers, from
the uppermost layer in order, are referred. A region in which there is a
three-dimensional structure 40 in the upper layer of the two adjacent
layers, or a region which is determined to require a support material 68
is set to a first region, and a region, in which there is no
three-dimensional structure 40 in the lower layer of the two adjacent
layers and which correspond to the first region, is set to a second
region (the same region as the first region in the XY plane). In this
case, in order to support the first region of the upper layer, the first
region is determined to need the support material 68. This determination
is sequentially performed from the uppermost layer to the lowermost layer
in this order.

[0065] For example, as shown in FIG. 11, if it is assumed that the slice
plane 56 (hereinafter, referred to as "a lower layer 56") shown in FIG. 7
and the slice plane 60 (hereinafter, referred to as "an upper layer 60")
shown in FIG. 9 are adjacent layers, when the sectional images of the
respective layers are superimposed in the Z-axis direction, an image
shown in FIG. 11 is obtained. At this time, the region directly under the
sectional image 62B (first region) of the upper layer 60, that is, the
region (second region) corresponding to the sectional image 62B of the
lower layer 56 becomes a region in which the three-dimensional structure
40 does not exist. Therefore, as shown in FIG. 12, the region 64
corresponding to the sectional image 62B of the lower layer 56 is
determined as a region needing the support material 68. Incidentally, in
the region corresponding to the sectional image 62A of the lower layer
56, since this region is a region overlapping the sectional image 58 of
the lower layer 56, that is, a region in which the model material exists
in the upper layer, this region is determined as a region not needing the
support material 68. Such determination is sequentially performed from
the uppermost layer to the lowermost layer in this order. Thus, the
support structure 42 needing the support material 68, as shown in FIG. 4,
is determined.

[0066] In step 106 (S106), support material data 30C of the support
structure 42 determined in step 104 (S104) are created. Since the support
structure 42 is required to be removed after the entire forming including
the support structure 42 is completed, the support structure 42 is made
of a material which is easily crushed, water-dissolved and hot-melted
compared to the model material. Thus, since the support material has low
density and strength compared to those of the model material, there is a
possibility that cannot support a heavy body portion located thereon.
Further, since the support material has a high volume contraction rate,
there is a case where the shape of the support structure 42 is varied
over time.

[0067] In the present exemplary embodiment, in the case where the support
structure 42 is viewed as a section parallel to the XY plane, the support
material data 30C are created such that the model material and the
support material are disposed in an arrangement pattern containing the
model material and the support material. Specifically, for example, as
shown in FIG. 13A, the arrangement pattern is set to a grid-like pattern
in which the model materials 66 and the support materials 68 are
alternately arranged. In this case, it is preferable that the model
materials 66 and the support materials 68 are uniformly arranged.
Further, the size of the model material 66 in one grid may be set to the
size of the minimum unit that can be ejected through the model material
ejection head 16, and may also be set to be a certain degree of size.
Further, the shapes of all the model materials 66 may not be the same as
each other. In addition, the support materials 68 are also the same as
the model materials 66 in the above characteristics.

[0068] As such, in the case where the model materials 66 as well as the
support materials 68 are arranged in the support structure 42, both
prevention of decrease in strength of the support structure 42 and ease
of removal of the support structure 42 are realized, compared to in the
case where only the support materials 68 are arranged in the support
structure 42. Further, the volume contraction rate is lowered, thereby
preventing the shape of the support structure 42 from being varied over
time.

[0069] The arrangement pattern, as shown in FIG. 13B, may be set to a
gradation-like arrangement pattern. In this case, according to being
close to the three-dimensional structure 40, the rate of the support
material 68 in the support structure 42 (the amount of the support
material 68 per unit area) increases, and, according to being distant
from the three-dimensional structure 40, the rate of the model material
66 in the support structure 42 (the amount of the model material 66 per
unit area) increases. Therefore, according to being close to the
three-dimensional structure 40, the strength of the support structure 42
decreases, and thus the stripping of the support structure from the
three-dimensional structure 40 becomes easy. Further, according to being
distant from the three-dimensional structure 40, the strength of the
support structure 42 increases, so that it is easy to support the
three-dimensional structure 40 formed on the support structure detached
in a height direction, and it is possible to prevent the shape of the
support structure 42 from being varied over time due to volume
contraction. Accordingly, both prevention of decrease in strength of the
support structure 42 and ease of removal of the support structure 42 are
more effectively realized. Further, the variation of the shape of the
support structure 42 over time is prevented.

[0070] The change of the rate of the support material 68 (the change of
the amount of the support material 68 per unit area) may be arbitrarily
set. For example, the change thereof may be constant, and may also be
increased according to being close to the three-dimensional structure 40
and be decreased according to being distant from the three-dimensional
structure 40.

[0071] The arrangement pattern, as shown in FIG. 13C, may be set to a
random arrangement pattern. In this case, the arrangement of the model
materials 66 and the support materials 68 in the support structure 42 is
randomly determined. The random density may be changed for each region of
the support structure 42.

[0072] As such, the support material data 30C are created such that the
model materials 66 and the support materials 68 are arranged in the
support structure 42 in the arrangement pattern containing the model
materials 66 and the support materials 68, and the created support
material data 30C are stored in the storage unit 30.

[0073] In the case where the arrangement pattern of the model materials 66
and the support materials 68 is set to the grid-like arrangement pattern
as shown in FIG. 13A, it is preferable that, as shown in FIG. 14, the
arrangement pattern of each layer in the support structure 42 is set such
that the model materials 66 and the support materials 68 are alternately
arranged even in a height direction (laminating direction).

[0074] As such, in the case where the arrangement of the model materials
66 and the support materials 68 is a clear arrangement pattern, it is
preferable that the arrangement pattern is set such that the model
materials 66 and the support materials 68 are not continuously arranged
in a height direction, respectively.

[0075] Even in the case where the arrangement pattern of the model
materials 66 and the support materials 68 is set to the gradation-like
arrangement pattern as shown in FIG. 13B or in the case where the
arrangement pattern thereof is set to the random arrangement pattern as
shown in FIG. 13C, it is preferable that the arrangement pattern of each
of layer in the support structure 42 is set such that the model materials
66 and the support materials 68 are not continuously arranged as much as
possible in a height direction, respectively. For example, as shown in
FIG. 15, the arrangement pattern of each layer is set such that different
arrangement patterns 70 and 72 are adjacent to each other. In this case,
for example, the model materials 66 and the support materials 68 may not
be continuously arranged as much as possible in the height direction,
respectively, by changing random seed or random algorithm used when
setting the gradation-like arrangement pattern or the random arrangement
pattern or by performing three-dimensional error diffusion or mask
processing.

[0076] Further, the arrangement pattern of the model materials 66 and the
support materials 68 may be arbitrarily set by a user. In this case, for
example, the user specifies an arrangement pattern in which the model
materials 66 are arranged in the support materials 68 in any shape of
column, ladder, and spiral.

[0077] The creation of the support material data 30C may be performed
while creating the slice data.

[0078] In the example of FIG. 4, a case where the support structure 42
exists directly under the model material is shown, but the support
material data 30C may be created such that the support structure 42
becomes a support structure having a flared shape toward a lower side as
well as directly under the model material.

[0079] For example, there is a case where fused deposition modeling (FDM)
is used as a lamination method or a case where self-supporting is
possible depending on the strength of the material even without the
support structure directly under the model material. In this case, the
support material data 30C may be created such that the support structure
is omitted to some degree.

[0080] Even in the case of a cube which does not geometrically need a
support structure, in the case where the dripping of the model material
occurs, there is a case where the precision of the surface of a
three-dimensional structure is deteriorated. Therefore, even when a
support structure is not geometrically needed, the support material data
30C may be created such that a support structure is formed around a
three-dimensional structure.

[0081] In step 108 (S108), an instruction for initiating the irradiation
with UV light is transmitted to the UV light source 22. Thus, the UV
light source 22 initiates the irradiation with UV light.

[0082] In step 110 (S110), modeling processing is executed. That is, the
XY scanning unit 24 is controlled such that the model material ejection
head 16 and the support material ejection head 20 scan the XY plane, the
modeling platform lifting unit 26 is controlled such that the modeling
platform 34 gradually descends in the Z-axis direction, the model
material ejection head 16 is controlled such that the model material is
ejected in accordance with the slice data created in step 102 (S102), and
the support material ejection head 20 is controlled such that the support
material is ejected in accordance with the support material data 30C
created in step 106 (S106).

[0083] In step 112 (S112), it is determined whether or not the formation
of the three-dimensional structure 40 and the support structure 42 is
completed. If the formation thereof is not completed, step 114 (S114)
proceeds, and if the formation thereof is completed, step 118 (S118)
proceeds.

[0084] In step 114 (S114), it is determined whether or not the timing of
performing the cleaning of the model material ejection head 16 and the
support material ejection head 20 comes. If the timing of performing the
cleaning thereof comes, step 116 (S116) proceeds. Meanwhile, if the
timing of performing the cleaning thereof does not come, step 110 (S110)
proceeds, and the modeling processing continues.

[0085] As the timing of performing the cleaning thereof, for example, each
time a predetermined period elapses and each time at least one of the
model material and the support material consumes a predetermined amount
are exemplified. However, the timing of performing the cleaning thereof
is not limited thereto.

[0086] In the case where the timing of performing the cleaning thereof is
set to each time a predetermined period elapses, it is preferable that
the clogging state of the head is measured by variously changing the
period, and the longest period of the periods during which the clogging
of the head does not occur is set as the timing of performing the
cleaning thereof. The reason for this is that, as the period becomes
shorter, the number of times of cleaning increases, and thus the time
taken to complete the modeling processing becomes longer. Therefore, the
unnecessary execution of the cleaning is prevented.

[0087] In step 116 (S116), an instruction is transmitted to the XY
scanning unit 24 so as to move the model material ejection head 16 and
the support material ejection head 20 to a save area, and an instruction
is transmitted to the cleaning unit 28 so as to perform the cleaning of
the model material ejection head 16 and the support material ejection
head 20. Thus, the model material ejection head 16 and the support
material ejection head 20 are moved to the save area, and the cleaning
unit 28 cleans the model material ejection head 16 and the support
material ejection head 20. Meanwhile, in the case where the timing of
performing the cleaning thereof is set to each time at least one of the
model material and the support material consumes a predetermined amount,
only the head ejecting the material having been consumed in the
predetermined amount may be cleaned.

[0088] In step 118 (S118), an instruction for stopping the irradiation
with UV light is transmitted to the UV light source 22. Thus, the UV
light source 22 stops the irradiation with UV light.

[0089] As described above, in the present exemplary embodiment, since the
model materials as well as the support materials are arranged in the
support structure supporting the three-dimensional structure, both the
maintenance of strength of the support structure and the ease of removal
of the support structure are realized, compared to in the case where only
the support material is used in the support structure. In addition, the
shape change over time is prevented by the maintenance of strength of the
support structure.

Second Exemplary Embodiment

[0090] Hereinafter, the second exemplary embodiment of the present
invention will be described. In the present exemplary embodiment, a case
of performing modeling processing while creating slice data and support
material data 30C will be described. Since the apparatus configuration is
the same as that of the first exemplary embodiment, a description thereof
will be omitted.

[0091] Next, operations of the present exemplary embodiment will be
described. FIG. 16 shows a flowchart of the three dimension forming
program 30A to be executed by the CPU 12A. The processing in FIG. 16 is
executed when the formation of a three-dimensional structure is
instructed from the external device.

[0092] First, in step 200 (S200), similarly to step 100 (S100) of FIG. 3,
modeling data 30B of the three-dimensional structure 40 are received from
an external device, and the received modeling data 30B are stored in the
storage unit 30.

[0093] In step 202 (S202), a region needing the support structure is
predicted. As shown in FIG. 17, although the formation of the
three-dimensional structure 40 is performed by sequentially laminating
the model materials from the grounded surface in the height direction,
even in the case where the support structure is not needed up to the
height at the modeling time, there is a case where the support structure
for supporting the three-dimensional structure is needed in the step of
advancing the modeling. For example, as shown in FIG. 17, regions 74 and
76 in the XY plane do not need the support structure at the time of
performing the modeling to the height thereof, but it is needed to
provide the support structure to the height at which the
three-dimensional structure appears because the three-dimensional
structure appears with the proceeding of the modeling. Therefore, in the
present exemplary embodiment, before the initiation of modeling, the
region needing the support structure is predicted.

[0094] Specifically, the projection region in the XY plane at the time of
projecting the three-dimensional structure 40 in the height direction is
obtained based on the modeling data 30B. In the case of looking down the
three-dimensional structure 40 shown in FIG. 4 directly from above in the
height direction, the three-dimensional structure 40 is seen as in FIG.
18A. Thus, the projection region in the XY plane is a projection region
78 as shown in FIG. 18B. Therefore, the inside of the projection region
78 is set to a region needing the support structure.

[0095] Next, as shown in FIG. 19, the projection region 78 is divided into
a plurality of blocks 80. Then, the maximum value of the height direction
is obtained for each block, and the support structure is defined up to
the obtained maximum value. Accordingly, it is possible to prevent the
support structure from being unnecessarily formed. FIG. 20 shows an
example of a case where the support structure 42 is defined up to the
obtained maximum value in the height direction for each block. Further,
FIG. 21 shows an example of a case where a large number of blocks 80
exist compared to the case of FIG. 20.

[0096] As shown in FIG. 21, with the increase in the number of blocks 80,
the effect of reducing the unnecessary support structure 42 is increased.
For example, the support structure 42 is set to requisite minimum. That
is, in the case where the unnecessary support structure is set to 0, it
is required to process all the pixels included in the projection region
78 while regarding these pixels as the blocks, but processing time
increases. Meanwhile, when the number of the blocks 80 is too small,
processing time decreases, but the unnecessary support structure 42
increases. Therefore, the number of the blocks 80 is set in consideration
of balance between the processing time and the reduction of the
unnecessary support structure 42.

[0097] For example, less one of the number of pixels included in the
projection region 78 and the number of layers (the number of slice data)
obtained by dividing the height of the three-dimensional structure 40 by
lamination pitch may be set as the number of the blocks 80.

[0098] In step 204 (S204), similarly to step 108 (S108) of FIG. 3, an
instruction for initiating the irradiation with UV light is transmitted
to the UV light source 22.

[0100] In step 208 (S208), similarly to step 106 (S106) of FIG. 3, the
support material data 30C of the support structure 42, predicted in step
202 (S202), are created.

[0101] Since steps 210 to 218 (S210 to S218) are the same as steps 110 to
118 (S110 to S118) of FIG. 1, descriptions thereof will be omitted.

[0102] As described above, in the present exemplary embodiment, since the
modeling processing is performed while creating the slice data and the
support material data 30C, the modeling time of the three-dimensional
structure 40 is decreased. Further, similarly to the first exemplary
embodiment, since the model materials as well as the support materials
are arranged in the support structure supporting the three-dimensional
structure, both the maintenance of strength of the support structure and
the ease of removal of the support structure are realized, compared to in
the case where only the support material is used in the support
structure. In addition, the shape change over time is prevented by the
maintenance of strength of the support structure.

[0103] In the case where the number of layers is equal to or more than the
number of pixels included in the projection region 78, that is, in the
case where the height of the three-dimensional structure 40 is relative
high, the modeling processing of the present exemplary embodiment may be
performed. Further, in the case where the number of layers is less than
the number of pixels included in the projection region 78, that is, in
the case where the height of the three-dimensional structure 40 is
relative low, the modeling processing having been described in the first
exemplary embodiment may be performed.

(Support Material)

[0104] Hereinafter, the support material will be described in detail.

[0105] The support material is a support material for an inkjet method.
The support material contains a hot water-soluble radiation-curable
compound and at least one polyglycerin-based compound selected from the
group consisting of fatty acid esters of polyglycerin, ethylene oxide
adducts of polyglycerin, and polypropylene oxide adducts of polyglycerin.

[0106] Here, the "hot water solubility" means that the compound cured
after irradiation with radioactive rays exhibits solubility in hot water
of at least 40.degree. C. to 90.degree. C. Further, the "solubility"
means that, when the cured compound is dipped into the hot water of the
above temperature range, the compound is dissolved in the hot water to
express fluidity, and the shape of the compound at the time of curing is
not maintained.

[0107] Further, the hot water in the present specification refers to water
of the above temperature range.

[0108] According to the present exemplary embodiment, when the support
material satisfies the above configuration, there is provided a support
material capable of forming a three-dimensional structure having
excellent shape accuracy.

[0109] Estimation mechanism exhibited by this effect is inferred as
follows.

[0110] In the related art, the formation of a three-dimensional structure
has been performed by an inkjet type ejection head using a
radiation-curable model material and a radiation-curable support
material. For example, a model material is ejected by ink jet and cured
by irradiation with radioactive rays to form a structure, and a support
material is ejected by ink jet and cured by irradiation with radioactive
rays to form a support structure, so as to form a structure having a
targeted shape, and then the support structure is removed, thereby
obtaining a three-dimensional structure.

[0111] Here, the support material for ink jet is required to have
viscosity to such a degree that the support material can be ejected from
the ejection head at a temperature (generally, a temperature of
45.degree. C. to 85.degree. C.) at the time of ejecting the support
material by the ejection head. On the other hand, from the viewpoint of
precisely forming a support structure having a desired shape by the
support material, it is required to suppress the movement of the support
material from the ejected position until the support material is cured by
irradiation with radioactive rays after the support material is ejected
from the ejection head.

[0112] In contrast to this, the support material for ink jet according to
the present exemplary embodiment contains a polyglycerin-based compound
selected from the above group. Therefore, even when the support material
has fluidity of low viscosity to such a degree that the support material
can be ejected from the ejection head at the time of ejecting the support
material, after the ejection of the support material, the temperature of
the support material is lowered, and thus the viscosity thereof is
increased, so as to decrease the fluidity thereof. Accordingly, the
movement of the support material from the ejected position is reduced,
and thus the movement of the support material is prevented until the
support material is cured by irradiation with radioactive rays, so as to
form a support structure having excellent shape accuracy. As a result,
since the support structure is excellent in shape accuracy, a
three-dimensional structure to be formed using the support material
according to the present exemplary embodiment together with a model
material is realized to have excellent shape accuracy.

[0113] Further, the support material according to the present exemplary
embodiment containing a radiation-curable compound and a
polyglycerin-based compound selected from the above group exhibits
excellent curability by irradiation with radioactive rays. Since the
melting temperature of the support material is increased after the
support material is cured by irradiation with radioactive rays compared
to before the support material is cured by irradiation with radioactive
rays, lamination is further performed on the support structure after the
curing to form the next support structure. Therefore, even in the case
where the support material is further ejected after the curing to be
landed, the deformation of the support structure due to the heat caused
by the ejection of the support material is less likely to occur.
Accordingly, a support structure excellent in shape accuracy is formed.

[0114] The support material is required to have removability after forming
the support structure, that is, after curing the support material. In
contrast to this, in the present exemplary embodiment, the support
material contains a hot water-soluble radiation-curable compound and a
polyglycerin-based compound selected from the above group. Since the hot
water-soluble radiation-curable compound exhibits solubility in hot water
and the polyglycerin-based compound is also a compound that can be
dissolved in hot water, when hot water is used at the time of removing
the support structure, the support structure is dissolved in hot water,
and thus the support structure can be easily removed.

[0115] Hereinafter, components of the support material according to the
present exemplary embodiment will be described in detail.

[0116] The support material according to the present exemplary embodiment
contains a hot water-soluble radiation-curable compound and a
polyglycerin-based compound. The support material may contain other
additives, such as a plasticizer, a radiation polymerization initiator, a
polymerization inhibitor, a surfactant, and a colorant, in addition to
the above components.

(Hot Water-Soluble Radiation-Curable Compound)

[0117] The radiation-curable compound is a compound which is cured
(polymerized) by radioactive rays (for example, ultraviolet rays and
electron beams). The radiation-curable compound may be a monomer, and may
also be an oligomer.

[0118] The "hot water solubility" means that the compound cured after
irradiation with radioactive rays exhibits solubility in hot water of the
aforementioned temperature range.

[0119] As the radiation-curable compound, compounds having a
radiation-curable functional group (radiation-polymerizable functional
group) are exemplified. Examples of the radiation-curable functional
group include ethylenically unsaturated double bonds (for example, an
N-vinyl group, a vinyl ether group, and a (meth)acryloyl group), an epoxy
group, and an oxetanyl group. Among these compounds, a compound having an
ethylenically unsaturated double bond (for example, an acryloyl group) is
preferable.

[0121] Among these, from the viewpoints of improving ejectability by an
inkjet method at low viscosity at the time of ejection, easily performing
the curing by irradiation with radioactive rays, and improving
removability using hot water after the curing, hydroxyethyl
(meth)acrylate, (meth)acrylamide, (meth)acryloyl morpholine, acrylic
acid, methoxytriethylene glycol acrylate, and methoxypolyethylene glycol
acrylate are preferable, and hydroxyethyl (meth)acrylate is more
preferable.

[0122] In the present specification, (meth)acylate means both acrylate and
methacrylate. Further, (meth)acryloyl means both acryloyl group and
methacryloyl group.

Viscosity of Radiation-Curable Compound

[0123] The viscosity (23.degree. C.) of the radiation-curable compound is
preferably 5 mPas to 80 mPas, more preferably 8 mPas to 60 mPas, and
further more preferably 10 mPas to 50 mPas.

[0124] The viscosity may be measured according to the measurement method
using RHEOMAT 115 (manufactured by Contraves) to be described later.

Content of Radiation-Curable Compound

[0125] The content of the radiation-curable compound is preferably 40% by
weight to 80% by weight, and more preferably 45% by weight to 65% by
weight, with respect to the total amount of the support material.

(Polyglycerin-Based Compound)

[0126] The support material according to the present exemplary embodiment
contains at least one polyglycerin-based compound selected from the group
consisting of fatty acid esters of polyglycerin, ethylene oxide adducts
of polyglycerin, and polypropylene oxide adducts of polyglycerin.

[0127] As the polyglycerins in the fatty acid esters of polyglycerin,
polygylcerins obtained by polymerization of two glycerin molecules to
twenty glycerin molecules are preferable, and examples thereof include
diglycerin, triglycerin, tetraglycerin, pentaglycerin, hexaglycerin,
heptaglycerin, octaglycerin, nonaglycerin, decaglycerin, undecaglycerin,
and dodecaglycerin. Among these polygylcerins, tetraglycerin,
hexaglycerin, or decaglycerin is preferable.

[0128] As the fatty acid, fatty acids of 16 carbon atoms to 20 carbon
atoms are preferable, and examples thereof include saturated fatty acids,
such as palmitic acid, stearic acid, and arachidic acid.

[0129] As the polyglycerins in the ethylene oxide adducts of polyglycerin
and polypropylene oxide adducts of polyglycerin, the above polyglycerins
in the fatty acid esters of polyglycerin are preferably exemplified.

[0130] Ethylene oxide or propylene oxide is added in an amount of
preferably 60 mol to 120 mol, and more preferably 80 mol to 100 mol.

[0131] The polyglycerin-based compound may be used alone or as a
combination of two or more.

[0132] As examples of combinations of two or more, mixtures of fatty acid
esters of polyglycerin with ethylene oxide adducts of polyglycerin or
polypropylene oxide adducts of polyglycerin are exemplified.
Specifically, a mixture of stearic acid ester of polyglycerin (for
example, stearic acid ester of decaglycerin) with ethylene oxide adduct
of polyglycerin (for example, ethylene oxide adduct of diglycerin) is
exemplified.

[0133] In the case where fatty acid esters of polyglycerin (a) is used in
combination with ethylene oxide adducts of polyglycerin or polypropylene
oxide adducts of polyglycerin (b), the weight ratio thereof (a:b) is in a
range of preferably 70:30 to 90:10, and more preferably 75:25 to 85:15.

[0134] The HLB value of the polyglycerin-based compound (Hydrophile
Lipophile Balance/the HLB value of a mixture thereof in the case where
two or more kinds of polyglycerin-based compound are used as a
combination thereof) is preferably 7 to 13, and more preferably 8 to 12.
When the HLB value thereof is 7 or more, the solubility of the support
material in hot water is improved. Further, when the HLB value thereof is
13 or less, the performance in increase of viscosity of the support
material after the ejection of the support material from the ejection
head is further increased, and thus the shape accuracy of the support
structure is further improved.

Viscosity of Polyglycerin-Based Compound

[0135] It is preferable that the polyglycerin-based compound is solid at
room temperature (23.degree. C.).

[0136] The temperature at the time of ejecting the support material by an
inkjet type ejection head is 70.degree. C., and the viscosity of the
polyglycerin-based compound at this temperature is preferably 200 mPas to
1500 mPas, more preferably 400 mPas to 1200 mPas, and further more
preferably 600 mPas to 1000 mPas.

[0137] The viscosity may be measured according to the measurement method
using RHEOMAT 115 (manufactured by Contraves) to be described later.

Content of Polyglycerin-Based Compound

[0138] The content of the polyglycerin-based compound (the total content
thereof in the case where two or more kinds of polyglycerin-based
compound are used as a combination thereof) is preferably 5% by weight to
45% by weight, more preferably 10% by weight to 35% by weight, and
further more preferably 15% by weight to 30% by weight, with respect to
the total amount of the support material.

(Plasticizer)

[0139] The support material according to the present exemplary embodiment
may further contain a plasticizer.

[0140] As the plasticizer, a non-radiation-curable polymer is exemplified.
The non-radiation-curable polymer refers to a polymer in which a curing
(polymerization) reaction is not caused by radiation (for example,
ultraviolet rays or electron beams).

[0141] The non-radiation-curable polymer is preferably at least one
selected from the group consisting of polyether polyols, castor oil
polyols, and polyester polyols.

Polyether Polyols

[0142] Examples of polyether polyols include polymers of polyhydric
alcohols, adducts of polyhydric alcohols and alkylene oxide, and
ring-opening polymers of alkylene oxide.

[0151] Examples of cyclic ester compounds include .epsilon.-caprolactone
and .beta.-methyl-.delta.-valerolactone.

[0152] Here, the non-radiation-curable polymer, together with the
above-mentioned various polyols, may be used in combination with
polyhydric alcohols. In particularly, polyhydric alcohols may be used in
combination with polyester polyols. That is, as the non-radiation-curable
polymer, mixtures of polyester polyols and polyhydric alcohols are
exemplified.

[0153] The content of polyhydric alcohols used in combination with the
above-mentioned various polyols may be 30% by weight to 60% by weight
(preferably 35% by weight to 50% by weight) with respect to the total
amount of the radiation-curable polymer. Particularly, in the case where
a mixture of polyester polyol and polyhydric alcohol is used, the ratio
thereof (polyester polyol/polyhydric alcohol) may be 30/70 to 10/90
(preferably 25/75 to 20/80).

[0154] Examples of polyhydric alcohols include the polyhydric alcohols
exemplified in the description of polyether polyols.

Weight Average Molecular Weight of Non-Radiation-Curable Polymer

[0155] The weight average molecular weight of the non-radiation-curable
polymer is preferably 200 to 1,000, and more preferably 250 to 850.

[0156] The weight average molecular weight of the non-radiation-curable
polymer is a value measured by gel permeation chromatography (GPC) in
which polystyrene is used as a standard material.

Viscosity of Non-Radiation-Curable Polymer

[0157] The viscosity (25.degree. C.) of the non-radiation-curable polymer
is preferably 200 mPas or less, more preferably 100 mPas or less, and
further more preferably 70 mPas or less.

[0158] The viscosity may be measured according to the measurement method
using RHEOMAT 115 (manufactured by Contraves) to be described later.

Content of Plasticizer

[0159] The content of the plasticizer is preferably 25% by weight to 60%
by weight, more preferably 30% by weight to 55% by weight, and further
more preferably 35% by weight to 50% by weight, with respect to the total
amount of the support material.

[0160] The plasticizer may be used alone or as a combination of two or
more kinds thereof.

(Radiation Polymerization Initiator)

[0161] As the radiation polymerization initiator, well-known
polymerization initiators, such as a radiation radical polymerization
initiator and a radiation cationic polymerization initiator, are
exemplified.

[0164] The content of the radiation polymerization initiator is preferably
1% by weight to 10% by weight, and more preferably 3% by weight to 5% by
weight, with respect to the radiation-curable compound.

[0165] The radiation polymerization initiator may be used alone or as a
combination of two or more kinds thereof.

[0170] The content of the surfactant is preferably 0.05% by weight to 0.5%
by weight, and more preferably 0.1% by weight to 0.3% by weight, with
respect to the radiation-curable compound.

[0171] The surfactant may be used alone or as a combination of two or more
kinds thereof.

(Other Additives)

[0172] Examples of other additives, in addition to the above additives,
include well-known additives, such as a colorant, a solvent, a
sensitizer, a fixing agent, a fungicide, a preservative, an antioxidant,
an ultraviolet absorber, a chelating agent, a thickener, a dispersant, a
polymerization accelerator, a penetration enhancer, and a wetting agent
(humectant).

(Characteristics of Support Material)

[0173] The surface tension of the support material is in a range of 20
mN/m to 40 mN/m.

[0174] Here, the surface tension is a value measured by a Wilhelmy type
surface tension meter (manufactured by Kyowa Interface Science Co., Ltd.)
under an environment of a relative humidity (RH) of 55% at 23.degree. C.

[0175] The viscosity (23.degree. C.) of the support material is in a range
of 30 mPas to 50 mPas.

[0176] The temperature at the time of ejecting the support material by an
inkjet type ejection head is 70.degree. C., and the viscosity of the
support material at this temperature is preferably 5 mPas to 20 mPas,
more preferably 8 mPas to 18 mPas, and further more preferably 10 mPas to
15 mPas.

[0177] The viscosity is a value measured by using RHEOMAT 115
(manufactured by Contraves) as a measurement device and setting
measurement temperature to the above temperature under a condition of a
shear rate of 1400 s-1.

(Model Material)

[0178] Hereinafter, the model material will be described.

[0179] The model material contains a radiation-curable compound
(radiation-curable compound for model material). The model material may
further contain other additives, such as a radiation polymerization
initiator, a polymerization inhibitor, a surfactant, and a colorant, in
addition to the above-mentioned components.

[0180] As the radiation-curable compound used for the model material
(radiation-curable compound for model material), compounds having a
radiation-curable functional group (radiation-polymerizable functional
group) are exemplified. Examples of the radiation-curable functional
group include ethylenically unsaturated double bonds (for example, an
N-vinyl group, a vinyl ether group, and a (meth)acryloyl group), an epoxy
group, and an oxetanyl group. As the radiation-curable compound, a
compound having an ethylenically unsaturated double bond group
(preferably, a (meth)acryloyl group) is preferable.

[0181] Specific examples of the radiation-curable compound for the model
material include urethane (meth) acrylate, epoxy (meth)acrylate, and
polyester (meth)acrylate. Among these, urethane (meth) acrylate is
preferable as the radiation-curable compound for the model material.

[0182] The content of the radiation-curable compound for the model
material is preferably 90% by weight to 99% by weight, and more
preferably 93% by weight to 97% by weight, with respect to the total
amount of the model material.

[0183] Particularly, in the radiation-curable compound for the model
material, it is preferable that urethane (meth)acrylate is used in
combination with another radiation-curable compound (for example,
monofunctional or multifunctional (meth)acrylate). In this case, the
content of urethane (meth)acrylate is preferably 10% by weight to 60% by
weight, and more preferably 20% by weight to 50% by weight, with respect
to the total amount of the model material. Further, the content of the
above another radiation-curable compound is preferably 40% by weight to
75% by weight, and more preferably 50% by weight to 65% by weight, with
respect to the total amount of the model material.

[0184] The radiation-curable compound for the model material may be used
alone or as a combination of two or more kinds thereof.

[0185] As the radiation polymerization initiator, polymerization
inhibitor, surfactant, and colorant, which are used for the model
material, the components exemplified in the support material can be used.
The characteristics of the model material also are exemplified in the
same range as the characteristics of the support material.

(Method of Manufacturing Three-Dimensional Structure)

[0186] Through the three dimension forming apparatus 10 according to the
present exemplary embodiment, a method of manufacturing a
three-dimensional structure, including the steps of: ejecting a
radiation-curable model material by an inkjet method and curing the
ejected radiation-curable model material by irradiation with radioactive
rays to form a three-dimensional structure; and ejecting a support
material by an inkjet method and curing the ejected support material by
irradiation with radioactive rays to form a support structure supporting
at least a part of the three-dimensional structure, is carried out. In
the method of manufacturing a three-dimensional structure according to
the present exemplary embodiment, after the three-dimensional structure
is formed, the support structure is removed by dissolving the support
structure in hot water of 40.degree. C. to 90.degree. C. (preferably
60.degree. C. to 90.degree. C., and more preferably 60.degree. C. to
80.degree. C.), so as to form the three-dimensional structure.

[0187] Specifically, a method of dipping a three-dimensional structure
having a support structure into hot water and thus dissolving the support
structure to remove the support structure (dipping method), a method of
injecting hot water to a three-dimensional structure having a support
structure and thus dissolving the support structure to remove the support
structure by water pressure (injection method), or the like is employed.
In terms of a simple removal method, the removal of the support structure
by the dipping method is more preferable. In the dipping method,
ultrasonic irradiation is also preferably used.

[0188] The obtained structure may be subjected to post-treatment, such as
abrasion treatment.

[0189] The three dimension forming apparatus 10 may be provided with a
model material cartridge accommodating the model material and detachably
attached to the three dimension forming apparatus 10. Similarly, the
three dimension forming apparatus 10 may be provided with a support
material cartridge accommodating the support material and detachably
attached to the three dimension forming apparatus 10.

[0190] Hereinafter, the present invention will be described in more detail
with reference to Examples.

[0191] However, the present invention is not limited to these Examples.
Here, "parts" are based on weight, unless otherwise specified.

Example 1

Support Material SA1

Preparation of Polyglycerin-Based Compound 1

[0192] 80 parts of decaglycerin tristearate and 20 parts of
diglycerin-ethylene oxide 100 mol adduct are heated and stirred from
100.degree. C. to 200.degree. C. until they are melted, and the molten
product is cooled to room temperature (25.degree. C.), so as to obtain
polyglycerin-based compound 1 having a HLB value of 10.

[0202] The above components are mixed with each other, so as to prepare
support material SA1.

Example 2

[0203] Support material is obtained in the same manner as in Example 1,
except that the polyglycerin-based compound 1 used in Example 1 is
changed to polyglycerin-based compound 2 prepared as follows.

Preparation of Polyglycerin-Based Compound 2

[0204] 20 parts of decaglycerin tristearate and 80 parts of
diglycerin-ethylene oxide 100 mol adduct are heated and stirred from
100.degree. C. to 200.degree. C. until they are melted, and the molten
product is cooled to room temperature (25.degree. C.), so as to obtain
polyglycerin-based compound 2 having a HLB value of 9.5.

Example 3

[0205] Support material is obtained in the same manner as in Example 1,
except that the hydroxyethyl acrylate (HEA) used in Example 1 is changed
to acryloyl morpholine.

Example 4

[0206] Support material is obtained in the same manner as in Example 1,
except that the plasticizer (castor oil, URIC H-31) used in Example 1 is
changed to polyester polyol (P-400, manufactured by ADEKA CORPORATION)

Comparative Example 1

[0207] Support material is obtained in the same manner as in Example 1,
except that the hydroxyethyl acrylate (HEA), polymerization initiator
(DAROCUR 1173), and polymerization inhibitor (GENORAD 16) in Example 1
are not used.

Comparative Example 2

[0208] Support material is obtained in the same manner as in Example 1,
except that the polyglycerin-based compound 1 in Example 1 is not used.

Comparative Example 3

[0209] Support material is obtained in the same manner as in Example 3,
except that the polyglycerin-based compound 1 in Example 3 is not used.

Comparative Example 4

[0210] Support material is obtained in the same manner as in Example 4,
except that the polyglycerin-based compound 1 in Example 4 is not used.

Comparative Example 5

[0211] Support material is obtained in the same manner as in Example 1,
except that the polyglycerin-based compound 1 in Example 1 is changed to
an ethylene-vinyl acetate copolymer (trade name: 701D, manufactured by
Moribe Stores Inc.).

(Evaluation)

Evaluation of Inkjet Ejection Applicability

[0212] The inkjet ejection applicability of support material is evaluated
by measuring viscosity.

[0213] The viscosity at 70.degree. C. is measured by RHEOMAT 115
(manufactured by Contraves) under a condition of a shear rate of 1400
s-1.

[0219] POLARIS head (model number: PQ512/85), manufactured by Fujifilm
Dimatrix Inc., is selected as an inkjet head, SUBZERO-055 (intensity of
100 w/cm), manufactured by INTEGRATION TECHNOLOGY LTD., is selected as an
ultraviolet irradiation light source, they are provided in a forming
apparatus including a drive unit and a control unit, and this forming
apparatus is used as a forming apparatus for test. In the forming
apparatus, the inkjet head and the light source are reciprocally moved
together, support material layers having a thickness of 20 .mu.m are
laminated, and curing treatment are performed by ultraviolet irradiation
for each scanning once, so as to form a support structure by the support
material. Further, in the forming apparatus, the support material passes
through a Profile Star A050 filter (filtration accuracy 5 .mu.m),
manufactured by NIHON PALL LTD., via a TYGON 2375 chemical-resistant
tube, manufactured by SAINT-GOBAIN.TM. K.K., from a storage tank by a
feed pump under a light-blocking condition, so as to remove foreign
materials from the support material, and then the resulting support
material is supplied to the inkjet head.

[0220] The resolution pattern is scanned by the above forming apparatus to
form a support structure pattern.

[0221] The shape accuracy (resolution) is evaluated by whether the support
structure pattern can be resolved to such a degree of size.

Evaluation of Hot Water Removability

[0222] The support structure pattern formed in the evaluation of shape
accuracy (resolution) is dipped into hot water of 60.degree. C.

[0223] The hot water removability is evaluated by whether or not the
support structure pattern is dissolved.

Evaluation Criteria

[0224] A (.largecircle.): the support structure pattern is dissolved and
solids are disappeared within 5 minutes

[0225] B (.DELTA.): the support structure pattern is dissolved, but it
takes more than 30 minutes for solids to disappear

[0226] C (X): the support structure pattern is not dissolved, and solids
remain

[0227] From the results of Table 1, it is found that, in Examples in each
which a support material containing a hot water-soluble radiation-curable
compound and a specific polyglycerin-based compound is used, the shape
accuracy of a support structure to be formed is excellent, compared to
Comparative Examples 2, 3, and 4 in each which a support material does
not contain polyglycerin-based compound.

Viscosity Adjustment of Support Material

[0228] Hereinafter, the experimental results of viscosity adjustment of
support material will be described. FIG. 23 shows the results of
evaluating the viscosity of the support material at 55.degree. C.
(temperature of ejection head) and the solubility of the support material
after UV curing, with regard to the composition of the plurality of
patterns. Evaluation criteria are as follows.

[0234] It is found that, when the viscosity and solubility of the
composition FXS 52 in which HEA is replaced by HEAA (hydroxyethyl
acrylamide) are evaluated with reference to the composition FXS 49
containing hydroxyethyl acrylate (HEA), hydroquinone momomethyl ether
(MEHQ), bisacylphosphine oxide (BAPO), IRGACURE 379
(2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-o-
ne), manufactured by BASF Corporation), ITX (2-isopropylthioxanthone),
TEGO WET270 (polyether-modified siloxane copolymer, manufactured by
Evonik Japan), and P-400 (polyester polyol), the composition FXS 52 is
dissolved in a short period of time by ultrasonic application after UV
curing.

[0235] HEAA has very high viscosity due to the hydrogen bond of an
internal amide group thereof, and has high shape holding properties after
curing. The viscosity of HEAA at 55.degree. C. (temperature of ejection
head) is 43.2 mPas, which is high, is not sufficiently lowered even
though the amount of P-400, which is a non-UV-curable component, is
increased. The reason for this is that the original viscosity of P-400 at
55.degree. C. is 17 mPas. Thus, there is an attempt to lower the
viscosity of HEAA by using low-viscosity monofunctional monomer HEA or
OH-modified castor oil (H31), which is a low-viscosity non-UV-curable
component, until HEAA can be used in an inkjet method.

[0236] As shown in FIG. 23, in the viscosity adjustment with HEA and H31,
trade-off relationship between solubility and viscosity in water occurs,
and the composition FXS 63 is a barely acceptable level of composition.

[0237] Thus, a water-soluble support material composition, which is water
soluble after UV curing and which has viscosity capable of being ejected
by an inkjet method, is found. As the requirements necessary for the
water-soluble support material, the following four points are
exemplified.

[0238] (1) 50 wt % or more of non-UV-curable component is needed.

[0239] (2) di- or more functional reaction components are not used.

[0240] (3) mono-functional monomer having high sensitivity is selected,
and cross-linking reactions caused by side reactions are prevented.

[0241] (4) polymer after UV curing and non-UV-curable component are
phase-separated from each other and combined with each other.

[0242] A thermal fusible support material may be used without the
water-soluble support material. Examples of the thermal fusible support
material include water-soluble wax of powder liquefied by heating and
solidified by natural cooling, and urea powder.

[0243] In each of the above exemplary embodiments, a case where the
modeling platform 34 gradually descends in the Z-axis direction while the
model material ejection head 16 scans the XY plane has been described.
However, the model material ejection head 16 may gradually ascend in the
Z-axis direction while scanning the XY plane in a state in which the
modeling platform 34 is fixed. Further, both the modeling platform 34 and
the model material ejection head 16 may be moved so as to be separated in
the Z-axis direction.

[0244] The configuration of the three dimension forming apparatus 10
having been described in each of the above exemplary embodiments (refers
to FIG. 1) is an example. Unnecessary components may be deleted or novel
components may be added within a range that does not depart from the
spirit of the present invention.

[0245] The foregoing description of the exemplary embodiments of the
present invention has been provided for the purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise forms disclosed. Obviously, many modifications
and variations will be apparent to practitioners skilled in the art. The
embodiments were chosen and described in order to best explain the
principles of the invention and its practical applications, thereby
enabling others skilled in the art to understand the invention for
various embodiments and with the various modifications as are suited to
the particular use contemplated. It is intended that the scope of the
invention be defined by the following claims and their equivalents.